1
Q
What is Charles Darwin’s theory of evolution?
A
- survival of the fittest/natural selection
- organisms in a species show wide variation and have to compete for limited resources in an ecosystem
- the organisms that are best adapted would be more successful competitors and would be more lightly to survive, reproduce and pass on the adaptions to their offspring
- less well adapted organisms are less likely to survive and pass on their characteristics
- over time, successful adaptions become more common in the population and the species changes–it evolves
2
Q
What new discoveries have helped to develop the theory of natural selection?
A
- Darwin didn’t know why new characteristics appeared or how they passed on beneficial adaptations
- this was due to DNA being yet to be discovered
- we now know that adaptions are controlled by genes, new adaptions arise because of mutations, adaptions are passed on through genes
3
Q
How can reproductive isolation be caused by geographical isolation?
A
- a physical barrier divides a species, e.g. a river changes its course
- the two new populations are unable to mix
- different mutations create different new features in the two groups
- natural selection take place
- the conditions on each side will be slightly different, so the beneficial features will be different
- eventually, the two populations have such different features that they can not breed together to produce fertile offspring
- they have become reproductively isolated and the two groups are separate species
4
Q
Why do people disagree with Darwin?
A
- goes against religious believes, it was a plausible explanation for our own existence without the need for a ‘creator’
- Darwin couldn’t explain why new, useful characteristics appeared or how they were inherited
5
Q
What was Lamarck’s theory of evolution?
A
- Lamarck argued that if an organism used a characteristic a lot then it would become more developed
- he believed acquired characteristics could be passed to offspring
- people later concluded that acquired characteristics don’t have genetic basis, they can’t be passed on to the next generation
6
Q
Why is the theory of natural selection widely accepted?
A
- the theory was debated and tested independently by a wide range of scientists, no one has found conclusive evidence that the theory is wrong
- the theory offers a plausible explanation to many observations of animals and plants (physical characteristics and behavioural patterns)
